When two user equipment terminals (e.g., mobile communication devices) of a cellular network or other telecommunication system communicate with each other, their data path typically goes through the operator network. The data path through the network may include base stations and/or gateways. If the devices are in close proximity with each other, their data path may be routed locally through a local base station In general, communications between a network node such as a base station and a wireless terminal is known as “WAN” or “Cellular communication”.
It is also possible for two user equipment terminals in close proximity to each other to establish a direct link without the need to go through a base station. Telecommunications systems may use or enable device-to-device (“D2D”) communication, in which two or more user equipment terminals directly communicate with one another. In D2D communication, voice and data traffic (referred to herein as “communication signals”) from one user equipment terminal to one or more other user equipment terminals may not be communicated through a base station or other network control device of a telecommunication system. As such device-to-device (D2D) communications differ from “WAN” or “Cellular communication”. Device-to-device (D2D) communication has more recently also become known as “sidelink direct communication”.
D2D communication, e.g., sidelink direct communication, can be used in networks implemented according to any suitable telecommunications standard. A non-limiting example of such as standard is the 3rd Generation Partnership Project (“3GPP”) Long Term Evolution (“LTE”). The 3GPP standard is a collaboration agreement that aims to define globally applicable technical specifications and technical reports for present and future generation wireless communication systems. The 3GPP may define specifications for next generation mobile networks, systems, and devices. The 3GPP LTE is the name given to a project to improve the Universal Mobile Telecommunications System (“UMTS”) mobile phone or device standard to cope with future requirements. In one aspect, UMTS has been modified to provide support and specification for the Evolved Universal Terrestrial Radio Access (“E-UTRA”) and Evolved Universal Terrestrial Radio Access Network (“E-UTRAN”). E-UTRAN is another non-limiting example of a telecommunications standard with which D2D communication may be used.
A non-exhaustive list of 3GPP documents which describe, at least in part, device-to-device (D2D) communication (e.g., “sidelink direct communication”) include the following (all of which are incorporated herein by reference in their entireties):
3GPP TS 36.201 v12.1.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); LTE Physical Layer; General Description (Release 12) (2014 December);
3GPP TS 36.211 v12.4.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 12) (2014 December);
3GPP TS 36.212 v12.3.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and Channel Coding (Release 12) (2014 December);
3GPP TS 36.213 v12.0.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Layer Procedures (Release 12) (2013 December);
3GPP TS 36.214 v12.1.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Layer; Measurements (Release 12) (2014 December);
3GPP TS 36.300 v12.4.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall Description; State 2 (Release 12) (2014 December);
3GPP TS 36.304 v12.3.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) Procedures in Idle Mode (Release 12) (2014 December);
3GPP TS 36.306 v12.3.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) Radio Access Capabilities (Release 12) (2014 December);
3GPP TS 36.321 v12.4.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) Protocol Specification (Release 12) (2014 December);
3GPP TS 36.322 v12.1.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Link Control (RLC) Protocol Specification (Release 12) (2014 September);
3GPP TS 36.323 v12.2.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Packet data Convergence Protocol (PDCP) Specification (Release 12) (2014 December); and
3GPP TS 36.331 v12.4.0, Technical Specification, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC) Protocol Specification (Release 12) (2014 December).
A 3GPP RAN1 Working Group has been studying expanding LTE's functionality to allow for Device-to-Device (D2D) communication to enable Proximity Services (ProSe) for public safety and, certain non-public safety requirements (See, e.g., RP-122009). However, the 3GPP RAN1 Working Group has not fully sorted out the details concerning how the resource allocation and assignment is to be managed, both in-network and out-of-network. Rather, much of the discussion has been centered on resource allocation notification—how the time/frequency location of a block of resources is communicated by an eNB to a population of wireless terminals to determine where in time/frequency D2D discussions take place. In particular, much of the discussion at present concerns out of coverage communication and how D2D transmissions take place out-of-coverage.
It has been proposed that wireless terminals, both in-coverage and out-of-coverage, need to be aware of a resource pool (e.g., a pool of time/frequency resources) for device-to-device (D2D) communications, and that all device-to-device (D2D) active wireless terminals should know how they are to receive scheduling assignments for device-to-device (D2D) purposes. See, RR-140126 Draft TR36.843, V1.2.0, Study on LTE Device to Device Proximity Services; Radio Aspects, incorporated herein by reference in its entirety.
It is also accepted that there is “continuous network control and adaptive resources allocation between ProSe and other E-UTRAN services, as long as ProSe UEs are served by E-UTRAN”. That essentially means that when under network control and using E-EUTRAN resources, the D2D capable wireless terminal is under network control as depicted in FIG. 11. See, e.g., RR-140126 Draft TR36.843, V1.2.0, Study on LTE Device to Device Proximity Services; Radio Aspects.
3GPP RAN2, agreements discuss two modes of operation, Mode 1 (which is scheduled and in which the wireless terminal needs to be in radio resource control (RRC) connected mode in order to receive device-to-device (D2D) communications) and Mode 2 which is autonomous. See, e.g., “R2-14xxxx_draft_report_RAN2_85_Prague_(v0.1).doc”, retrieved from the meeting Report area of the 3GPP website: http://www.3gpp.org/ftp/tsg_ran/WG2_RL2/TSGR2_85/Report/. These agreements state, among other things:                All UEs (Mode 1 (“scheduled”) and Mode 2 (“autonomous”)) are provided with a resource pool (time and frequency) in which they attempt to receive scheduling assignments.        2 In Mode 1, a UE requests transmission resources from an eNB. The eNB schedules transmission resources for transmission of scheduling assignment(s) and data.        2a In Mode 1, the UE sends a scheduling request (D-SR or RA) to the eNB followed by a BSR based on which the eNB can determine that the UE intends to perform a D2D transmission as well as the required amount resources.        2b In Mode 1, it is for further study how the eNB indicates the transmission resources to the UE.        2c In Mode 1, the UE needs to be RRC Connected in order to transmit D2D communication        
3GPP TS36.213 V12.0.0 envisions the adaptation of an UL grant in some fashion for broadcast D2D. However the exact signaling of time frequency resources has not been specified. Furthermore, typically the D2D bandwidth to be used will be a subset of an UL carrier in order for the D2D to remain under network control.
What is needed, therefore, are methods, apparatus, and/or techniques for providing a D2D grant, and preferably a D2D grant having expression which incorporates and/or is consistent with legacy functionality. The methods, apparatus, and/or techniques provide benefits that reduce system complexity and improve communication flexibility and efficiency.